"SOLAR: Sun catchers tuned to crank out the juice"
EEs are turning a 19th-century invention into a 21st-century alternative-energy source. The last leg of a two-decades-long effort by the U.S. Energy Deaprtment to unleash superefficient solar power by 2011 is homing in on the so-called Stirling engine, which is being used to drive solar generators. DOE test site measurements suggest the setup could bring the cost of solar power on a par with traditional fossil fuels and hydroelectric sources � assuming the project engineers can balance the separate power feeds from farms of thousands of simultaneously online 25-kilowatt Stirling solar dishes. The heart of the design, the engine itself, was invented by the Scottish minister Robert Stirling in 1816. "The Stirling engine makes solar power so much more efficiently than photovoltaic solar cells can," said Robert Liden, chief administrative officer at Stirling Energy Systems Inc. (Phoenix). "That's because the Stirling solar dish directly converts solar heat into mechanical energy, which turns an ac electrical generator." The bottom line, he said, "is that large farms of Stirling solar dishes � say, 20,000-dish farms � could deliver cheap solar electricity that rivals what we pay for electricity today." Under a multiyear Energy Department contract that started in 2004, Stirling Energy Systems will supply Sandia National Laboratories with solar dishes for integration into full-fledged power-generation substations capable of direct connections to the existing U.S. power grid.